How do you delete a node given only a pointer to it in a linked list?
This unique problem tests your understanding of memory manipulation and pointer arithmetic in linked lists without access to the head.
Why Interviewers Ask This
Interviewers use this to see if candidates understand the limitations of singly linked lists. It tests creative problem-solving when standard deletion methods (accessing previous node) are unavailable. It also checks attention to detail regarding the last node scenario.
How to Answer This Question
Explain why standard deletion fails without the previous pointer. Propose the copy-and-delete strategy: copy next node's data to current, then bypass the next node. Explicitly mention that this cannot be done for the tail node. Discuss the implications of this modification on the list structure.
Key Points to Cover
- Copy next node's data
- Update next pointer
- Cannot delete tail node directly
- O(1) time complexity
Sample Answer
Since I cannot access the previous node, I will copy the value of the next node into the current node. Then, I will update the current node's next pointer to skip the next node, effectively deleting it. This works for all nodes except the tail, which must be handled separately or noted as impossible with just the pointer.
Common Mistakes to Avoid
- Attempting to access previous node
- Failing to handle the tail node exception
- Confusing singly and doubly linked list operations
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